Counter-rotating propellers have been proposed for boats, see for example, U.S. Pat. No. 1,482,381 to Cake; U.S. Pat. No. 4,604,032 to Brandt et al.; U.S. Pat. No. 2,067,023 to Schleicher; and U.S. Pat. No. 4,792,314 to McCormick. However, those propeller systems propose a cantilevered-type mounting to the engine shaft. This tends to lead to excessive vibration and potential alignment problems. Streamlined struts that are connected to a boat hull for holding and supporting engine shaft cutlass bearings that are located below the boat hull and near the propeller are known in the art.